docs: def load_tagged_classes(cls, tag, fail_silently=True):
          """
          Produce a sequence of all XBlock classes tagged with `tag`.
  
          fail_silently causes the code to simply log warnings if a
          plugin cannot import. The goal is to be able to use part of
          libraries from an XBlock (and thus have it installed), even if
          the overall XBlock cannot be used (e.g. depends on Django in a
          non-Django application). There is diagreement about whether
          this is a good idea, or whether we should see failures early
          (e.g. on startup or first page load), and in what
          contexts. Hence, the flag.
          """
          # Allow this method to access the `_class_tags`
          # pylint: disable=W0212
          for name, class_ in cls.load_classes(fail_silently):
              if tag in class_._class_tags:
                  yield name, class_